1. Field of the Invention
The present invention relates to a light guide plate typically used in a liquid crystal display (LCD), and particularly to a light guide plate with a reflective means and a process for making the same.
2. Description of the Prior Art
A light guide plate is one of the key optical members used in a plane light source of an LCD. Usually, the function of the light guide plate is to receive light beams from certain light sources or the ambient environment, and to emit the received light beams uniformly in a certain direction. The light guide plate functions as a kind of light channel, and should collect light beams efficiently, minimize any propagation loss of the light beams, and emit the light beams uniformly.
Accordingly, a typical light guide plate includes a light receiving portion for collecting light beams and a light emitting portion for emitting the light beams. The body of the light guide plate is made of a highly light transmissive material. Other portions or surfaces of the light guide plate do not need to receive light or emit light, and internal or external reflective means must be used thereat to prevent light beams from improperly entering or emitting from the light guide plate.
Referring to FIG. 3, a conventional plane light source comprises a light guide plate 10 and a pair of light sources 11 adjacent to the light guide plate 10. The light guide plate 10 has a light incidence surface 103, a bottom surface 104, a light emitting surface 101 opposite to the bottom surface 104, and three non-incident side surfaces 102. The light incidence surface 103 has a pair of light incident portions 1031 corresponding to the light sources 11, and a non-incident portion 1032.
Referring also to FIG. 4, three reflection means are used in the plane light source. A reflection plate 106 is disposed under the bottom surface 104, a reflection member 105 is disposed to cover the non-incident portion 1032, and a reflection frame 21 is disposed around the non-incident side surfaces 102.
However, tolerances inherent in the manufacturing process and inaccurate assembly generally result in a gap 22 being formed between the light guide plate 10 and the reflection frame 21. In operation of the plane light source, leakage of light beams takes place at the gap 22. That is, some light beams do not emit from the light emitting surface 101 but instead are lost at the gap 22. This leakage reduces the transmittance of the plane light source.
Moreover, the need for three different reflection means complicates the production process. The three reflection means are a significant expense that adds to the cost of the plane light source.
It is desired to provide a light guide plate with reflection means which overcomes the above-described problems.